EP0916430B1 - Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision - Google Patents

Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision Download PDF

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Publication number
EP0916430B1
EP0916430B1 EP19970119939 EP97119939A EP0916430B1 EP 0916430 B1 EP0916430 B1 EP 0916430B1 EP 19970119939 EP19970119939 EP 19970119939 EP 97119939 A EP97119939 A EP 97119939A EP 0916430 B1 EP0916430 B1 EP 0916430B1
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EP
European Patent Office
Prior art keywords
expansion
ceramic
oxide
acid
mgo
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19970119939
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German (de)
English (en)
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EP0916430A1 (fr
Inventor
Chemie-Ing. Haider Otmar
Prof. Dr.-Ing. Nowack Norbert
Günther Grill
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SHERA-WERKSTOFFTECHNOLOGIE GmbH
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SHERA-WERKSTOFFTECHNOLOGIE GmbH
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Priority to DE59713010T priority Critical patent/DE59713010D1/de
Priority to EP19970119939 priority patent/EP0916430B1/fr
Publication of EP0916430A1 publication Critical patent/EP0916430A1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
    • B22C1/185—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents containing phosphates, phosphoric acids or its derivatives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/08—Artificial teeth; Making same
    • A61C13/081—Making teeth by casting or moulding
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/20—Methods or devices for soldering, casting, moulding or melting

Definitions

  • the invention relates to a method for producing investment castings for medical purposes.
  • prosthetic components if they have to be manufactured individually for each patient, are made of biocompatible metals and alloys, for example based on titanium (Ti).
  • Palladium (Pd), nickel-chromium (NiCr), cobalt-chromium (CoCr) and made of glass-ceramic materials by appropriate molds are created, in which the liquid alloys or the liquid glass of the subsequent glass-ceramic introduced, for example cast. After solidification of the alloy or the glass-ceramic material, the mold is removed and you get the alloy casting.
  • investment materials are generally used, which are based on a ceramic system.
  • the biocompatible materials used in the fourth process step cool, they shrink from liquid to solid during the phase change and contract in the solid, ie solidified state. In the solid state, some materials undergo transformations, for example titanium, the ⁇ -titanium / ⁇ -titanium conversion at 882 ° C.
  • the shrinking processes and the expansion processes result in a casting which has considerable deviations from the wax model of the impression of a body part produced in the first method step. Even with deviations of +/- 0.3%, which corresponds to a relative change in length ⁇ L / L O ⁇ 30 ⁇ m / cm in the case of a rod-shaped output part of length L O , the implants produced in this way can no longer be inserted without problems into the human body. Perfect fit implants have persistent pain, allergies, tissue changes, healthy bone tissue deformations, decreasing biocompatibility, for example due to the risk of stress corrosion cracking and risk of breakage.
  • quartz-containing and quartz-free investment materials are known and common.
  • EP-A-0417527 discloses inter alia investment materials with the ceramic system MgO-SiO 2 -P 2 O 5 .
  • JP-5700955 describes the use of carboxylic acids in ceramic investment materials.
  • the previously used quartz-free investment materials have extremely low thermal expansion coefficients, which are unacceptable especially for the production of filigree precision castings and therefore are not used.
  • quartz-containing investments are unsuitable for the production of precision castings made of titanium (Ti), zirconium (Zr) or titanium (Ti) or zirconium (Zr) alloys, since the investment materials of the ceramic mold in the casting of the metals or whose alloys react given casting temperatures of 1,650 ° C to 1,800 ° C with the liquid metals or their alloys. Due to numerous chemical reactions at the phase boundary between the ceramic mold and the liquid metals, the metals or their alloys absorb oxygen from the silicon dioxide (SiO 2 ), which leads to embrittlement of the metals at the surface, called "alpha-case" formation. as well as a loss of high corrosion resistance lead the metals.
  • SiO 2 silicon dioxide
  • quartz-containing potting compounds Another disadvantage of the quartz-containing potting compounds is given in the low softening temperatures thereof, which are in a temperature range between 1200 ° C and 1300 ° C.
  • the casting temperatures When casting metals or metal alloys with high melting temperatures, such as titanium (Ti) or its alloys, the casting temperatures of about 1650 ° C to 1800 ° C, thus additional thermal instabilities occur that bring about
  • the present invention is accordingly based on the object of specifying a method with which the expansion of ceramic investment materials can be set and controlled specifically, in particular as a function each of the materials to be cast and the respective processing process.
  • the technical solution is a method according to claim 1.
  • quartz-free ceramic investment materials are used in the process according to the invention, the expansion of which is specifically and precisely controlled and adjusted by the process. Quartz-free investments have a uniform expansion, ie they have a nearly constant linear expansion coefficient. This almost linear expansion behavior gives the possibility of an accurate, targeted and essentially predictable influence on the expansion.
  • the expansion of quartz-free ceramic investment materials can be precisely controlled by the addition of an organic acid and specifically adjusted by the proportion of magnesium oxide (MgO) in the oxide ceramic mixture of the embedding compound and the proportion of acid in the embedding compound.
  • the selection of the acid and the proportion of the magnesium oxide (MgO) in the oxide ceramic mixture and the proportion of acid in the investment material are selectable and tunable depending on the materials to be processed later and the process used.
  • the acid is a solid substance.
  • the acid can be added to the embedding compound in a particularly simple manner.
  • the acid is degradable without residue on heating.
  • the acid is very soluble in water. This ensures that the acid can be evenly distributed in the investment and react.
  • Such acids can be added to the investment materials as solids, are very soluble in water and can be broken down without residue on heating.
  • the acids react with the magnesium oxide (MgO) during mixing and, in a first step, form readily water-soluble magnesium salts.
  • the pH is lowered to values below 2.
  • the surface of the reacting magnesium oxide particle is activated. Since in the investment material based on the monoammonium phosphate (NH 4 H 2 PO 4 ) contains more than stoichiometric magnesium oxide, hydrolysates of Mg (OH) 2 / (brucite) and the magnesium salts of the organic acids are formed. These hydrolysates have a high intrinsic volume. This results in the setting process, a strong expansion with values of up to 3%.
  • the acid accounts for up to 2% by weight.
  • the oxide ceramic mixture as the main component oxides with a high thermal and chemical stability.
  • the oxide components of the ceramic mixture are thus advantageously high-melting and behave thermochemically substantially inert. As a result, the risk of slagging reactions is low and the resistance of castings produced with process-based embedding compounds, in particular over quartz-containing ceramic embedding compounds, is improved.
  • the oxide ceramic mixture consists of magnesium oxide (MgO), zirconium dioxide (ZrO 2 ) and aluminum oxide (Al 2 O 3 ).
  • MgO magnesium oxide
  • ZrO 2 zirconium dioxide
  • Al 2 O 3 aluminum oxide
  • unstabilized zirconium dioxides (ZrO 2 ) and corundum ( ⁇ -Al 2 O 3 ) can be used.
  • Such oxide ceramic mixtures of the components MgO-ZrO 2 -Al 2 O 3 generally have extremely low thermal expansion values. The thermal expansion for such mixtures, for example, based on 900 ° C between values of 0.2% to 0.6%. Such low thermal expansion values are usually insufficient for the production of filigree precision castings.
  • the additions according to the invention and their proportions of the embedding compound make it possible to increase the setting expansion values of the ceramic system and thus prevent inaccuracies in the manufacture of filigree precision castings.
  • the components of the ceramic system MgO-ZrO 2 -Al 2 O 3 all have great thermal and chemical stabilities, so that the slagging tendencies are extremely low.
  • the components of the ceramic system MgO-ZrO 2 -Al 2 O 3 are substantially more resistant to strongly reducing liquid metals or metal alloys, in particular based on titanium (Ti) or zirconium (Zr), and especially for titanium (Ti ) -Feinguß suitable.
  • the proportion of magnesium oxide (MgO) in the oxide ceramic mixture is up to 20% by weight.
  • the proportion of magnesium oxide (MgO) in the oxide ceramic mixture from 5 wt .-% to 10 wt .-% of.
  • magnesium oxide (MgO) having a mean particle size of about 20 ⁇ m to 120 ⁇ m, preferably of about 80 ⁇ m
  • zirconium dioxide (ZrO 2 ) having an average particle size of about 20 ⁇ m to 120 ⁇ m, preferably of about 40 microns
  • alumina (Al 2 O 3 ) having an average particle size of about 20 microns to 200 microns, preferably of about 110 microns used.
  • the proportion of monoammonium phosphate (NH 4 H 2 PO 4 ) based on the oxide ceramic mixture is about 5% to 15%.
  • the component P 2 O 5 is unstable to liquid metals.
  • the component P 2 O 5 is converted at a melting point of about 1400 ° C, wherein the thermodynamic activity of the P 2 O 5 component is greatly reduced.
  • the low proportion of monoammonium phosphate (NH 4 H 2 PO 4 ) in the investment ensures that the P 2 O 5 content after thermal treatment is less than 3%. This is particularly important in the area of investment casting technology based on titanium (Ti) or titanium (Ti) alloys, since titanium (Ti) is highly reducing.
  • the mixing liquid is a silica sol solution, advantageously up to 40% silica sol solution.
  • the mixing liquid is a silica sol solution, advantageously up to 40% silica sol solution.
  • 15 ml to 40 ml, preferably 20 ml of mixing liquid are used per 100 g investment.
  • a process embedding compound for producing molds for precision casting of metals or their alloys in particular based on titanium (Ti), gold (Au), palladium (Pd), nickel-chromium (Ni-Cr ) and cobalt-chromium (Co-Cr) and / or glass-ceramic materials, in particular in medical technology and in particular in dental technology.
  • Fig. 1 shows the dilatometer curve of a quartz-containing investment, that is, the increase in volume associated with an increase in temperature of the investment.
  • the quartz-containing investment is bound with MgO / NH 4 H 2 PO 4 binder and mixed with a 40% silica sol solution ⁇ -cristobalite and ⁇ -quartz.
  • the expansion behavior of the materials of the cast objects to be produced differs from the expansion behavior of the molds produced with corresponding investment materials.
  • the result is that in particular larger Guß Sharee, for example in the dental field Moliedrige bridges, upon cooling in a temperature range between 600 ° C to 1000 ° C plastic deformations subject, which can not be reversed in a temperature range below about 400 ° C, since the cast object then reacts to changes in length predominantly elastic.
  • Fig. 2 shows the thermal expansion of a quartz-free investment, consisting of an oxide ceramic mixture of 45% unstabilized ZrO 2 , 43% ⁇ -Al 2 O 3 and 7% MgO, a share of 5% of the binder NH 4 H 2 PO 4 and a 40% Silica solution, of which 20 ml were used per 100 g investment.
  • MgO having an average grain size of 80 ⁇ m
  • unstabilized ZrO 2 having a mean grain size of 40 ⁇ m
  • ⁇ -Al 2 O 3 having a mean grain size of 110 ⁇ m were used for the oxide ceramic mixture.
  • Fig. 3 shows the influence of the proportion of magnesium oxide (MgO) on the setting expansion in an oxide ceramic mixture with a constant ratio of ZrO 2 to ⁇ -Al 2 O 3 in a size of 48% / 45%, a binder with respect to the oxide ceramic mixture 5% Proportion of NH 4 H 2 PO 4 , an addition of 0.5% citric acid as an organic acid and a 40% silica sol solution, wherein for 100 g investment material 20 ml were used. The mass ratio 48% ZrO 2 /45% ⁇ -Al 2 O 3 was kept constant. As based on the in Fig. 3 is shown, takes the setting expansion with increasing proportion of magnesium oxide, wherein at a proportion of 7% to 8% of the magnesium oxide, a substantially linear increase in the setting expansion is recorded.
  • MgO magnesium oxide
  • Fig. 4 shows the dependence of the setting expansion of the embedding mass each supplied proportion of the organic acid.
  • Curves 1 to 4 shown for various ceramic mixtures and acids.
  • 20 ml of a 40% strength silica sol solution were used as admixing liquid for 100 g of embedding compound.
  • the oxide ceramic mixture was used with different magnesium oxide contents, but always with a fixed ratio of unstabilized ZrO 2 / ⁇ -Al 2 O 3 , that is, the mass ratio of unstabilized ZrO 2 / ⁇ -Al 2 O 3 was 48% / 45% and was kept constant.
  • the curve marked 1 was recorded at a level of 7% magnesium oxide and a steadily increasing proportion of oxalic acid dihydrate.
  • the curve marked 2 was also recorded at an MgO content of 7%, but with a steadily increasing proportion of citric acid.
  • Curve 3 was recorded at a 15% level of MgO and a steadily increasing level of citric acid.
  • the ratio of ZrO 2 to ⁇ -Al 2 O 3 was kept constant at 48% - ZrO 2 /45% - ⁇ -Al 2 O 3 .
  • Curve 4 shows the course of the setting expansion when using a 7% MgO content with a continuously increasing proportion of tartaric acid.
  • citric acid in combination with 15% MgO at a citric acid content of more than 0.4% causes a setting expansion of almost 3%.
  • carboxylic acids such as malic acid, malonic acid and maleic acid.
  • a mold made from this investment was annealed at about 1000 ° C for 30 minutes. The mold was then sintered, causing it to contract by about 0.4%. Finally, the mold was cooled to room temperature so that ultimately the total expansion of the mold was about 2.3%.
  • liquid titania having a purity of 99.4% was poured into the mold at room temperature, with centrifugal casting in a 99.999% argon atmosphere also being used here in an induction furnace as in Example 2.
  • the castings thus produced had linear deviations ⁇ L / L 0 of the casting from the original part of about 20 ⁇ m / cm to 30 ⁇ m / cm.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Dental Preparations (AREA)
  • Dental Prosthetics (AREA)

Claims (9)

  1. Procédé pour la fabrication de pièces en fonte de précision pour applications médicales, dans lequel un modèle en cire est inclus dans une masse d'enrobage céramique sans quartz composée d'un mélange d'oxydes céramiques composé d'oxyde de magnésium, d'oxyde de zirconium et d'oxyde d'aluminium, d'un liant à base d'oxyde de magnésium et de monophosphate d'ammonium et d'un liquide d'addition pour la fabrication d'un moule de coulée, dans lequel la cire est ensuite éliminée par chauffage tandis que le moule de coulée est solidifié et l'opération de coulée est ensuite réalisée en introduisant des métaux, des alliages de ceux-ci ou du verre liquide pour le futur matériau vitrocéramique, servant de matériau de coulée, après le refroidissement desquels la pièce en fonte de précision peut être démoulée, caractérisé en ce que la masse d'enrobage est additionnée d'au moins un acide organique afin de contrôler et d'ajuster son expansion.
  2. Procédé selon la revendication 1, caractérisé en ce que l'acide est une matière solide.
  3. Procédé selon au moins l'une des revendications 1 et 2, caractérisé en ce que l'acide est un acide di- ou tricarboxylique selon la formule chimique R(COOH)x, où R = molécule de résidu organique et X = 2, 3.
  4. Procédé selon une ou plusieurs des revendications 1 à 3, caractérisé en ce que la proportion d'oxyde de magnésium (MgO) dans le mélange d'oxydes céramiques représente jusqu'à 20 % du poids.
  5. Procédé selon une ou plusieurs des revendications 1 à 4, caractérisé en ce que la proportion d'oxyde de magnésium (MgO) dans le mélange d'oxydes céramiques représente de 5 % à 10 % du poids.
  6. Procédé selon une ou plusieurs des revendications 1 à 5, caractérisé en ce que l'oxyde de magnésium et l'oxyde de zirconium sont employés avec une grosseur de grains moyenne d'environ 20 µm à 120 µm et l'oxyde d'aluminium avec une grosseur de grains d'environ 20 µm à 200 µm.
  7. Procédé selon une ou plusieurs des revendications 1 à 6, caractérisé en ce que la proportion de monophosphate d'ammonium (NH4H2PO4) du liant par rapport au mélange d'oxydes céramiques est d'environ 5 % à 15 % en poids.
  8. Procédé selon une ou plusieurs des revendications 1 à 7, caractérisé en ce que le liquide d'addition est une solution d'acide silicique.
  9. Procédé selon une ou plusieurs des revendications 1 à 8, caractérisé en ce que l'on utilise jusqu'à 40 ml de liquide d'addition pour 100 g de masse d'enrobage.
EP19970119939 1997-11-14 1997-11-14 Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision Expired - Lifetime EP0916430B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE59713010T DE59713010D1 (de) 1997-11-14 1997-11-14 Verfahren zur Steuerung und Einstellung der Expansion von keramischen Einbettmassen
EP19970119939 EP0916430B1 (fr) 1997-11-14 1997-11-14 Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision

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Application Number Priority Date Filing Date Title
EP19970119939 EP0916430B1 (fr) 1997-11-14 1997-11-14 Procédé pour le contrôle de l'expansion de matériau pour le moulage de précision

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EP0916430A1 EP0916430A1 (fr) 1999-05-19
EP0916430B1 true EP0916430B1 (fr) 2009-06-24

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202012103170U1 (de) 2012-08-22 2012-11-29 SHERA Werkstoff-Technologie GmbH & Co. KG Gußeinbettmasse für dentalmedizinische Anwendungen
DE102013109039A1 (de) 2012-08-22 2014-02-27 SHERA Werkstoff-Technologie GmbH & Co. KG Verfahren zur Herstellung von Präzisionsgussteilen für dentalmedizinische Anwendungen

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE59914938D1 (de) * 1999-04-09 2009-02-05 Shera Werkstofftechnologie Gmb Verfahren zur Herstellung von Gusswerkstücken
DE10110687B4 (de) * 2001-03-06 2013-02-21 Norbert Nowack Verfahren zur Herstellung filigraner Präzisionsgussteile sowie keramische Gusseinbettmasse hierfür
DE10223883B4 (de) * 2002-05-29 2006-08-03 BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG Verfahren zur Herstellung eines zahntechnischen Gussteils
DE102004031607A1 (de) 2004-06-30 2006-02-09 Shera-Werkstofftechnologie Gmbh & Co. Kg Keramische Einbettmassen zur Herstellung von Präzisionsgußformen für Gußteile aus Titan, Zirkonium oder deren Legierungen
DE102010064142B4 (de) 2010-12-23 2019-06-13 BEGO Bremer Goldschlägerei Wilh. Herbst GmbH & Co. KG Einbettmasse zur Verwendung in einem Verfahren zur Herstellung einer Dental-Restauration mittels CAD-Cast-Verfahren
DE102013113560B3 (de) 2013-12-05 2015-05-28 SHERA Werkstoff-Technologie GmbH & Co. KG Keramische Einbettmasse und deren Verwendung sowie Verfahren zur Herstellung von Präzisionsgussteilen
DE102014103234A1 (de) 2014-03-11 2015-09-17 Anton Sawizki Verfahren zum Anfertigen eines Sekundärteils

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JPS579554A (en) * 1980-06-20 1982-01-19 Tokuyama Soda Co Ltd Mold material
US4591385A (en) * 1984-06-04 1986-05-27 Aremco Products, Inc. Die material and method of using same
JPS63141906A (ja) * 1986-12-03 1988-06-14 G C Dental Ind Corp 歯科鋳造用埋没材
DE3930750A1 (de) * 1989-09-14 1991-03-28 Krupp Medizintechnik Gusseinbettmasse, einbettmassenmodell, gussform und verfahren zur verhinderung des aufbluehens von einbettmassenmodellen und gussformen aus einer gusseinbettmasse
DE4210004A1 (de) * 1992-03-27 1993-09-30 Joachim Pajenkamp Verfahren und keramische Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan und keramisierbare Zusammensetzung für die Herstellung einer keramischen Gußform zur Herstellung von dentalen Gußwerkstücken aus Titan
RU2061572C1 (ru) * 1992-12-21 1996-06-10 Александр Васильевич Климкин Самотвердеющая смесь для изготовления литейных форм и стержней

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202012103170U1 (de) 2012-08-22 2012-11-29 SHERA Werkstoff-Technologie GmbH & Co. KG Gußeinbettmasse für dentalmedizinische Anwendungen
DE102013109039A1 (de) 2012-08-22 2014-02-27 SHERA Werkstoff-Technologie GmbH & Co. KG Verfahren zur Herstellung von Präzisionsgussteilen für dentalmedizinische Anwendungen
DE102013107900A1 (de) 2012-08-22 2014-05-28 SHERA Werkstoff-Technologie GmbH & Co. KG Gußeinbettmasse für dentalmedizinische Anwendungen

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Publication number Publication date
DE59713010D1 (de) 2009-08-06
EP0916430A1 (fr) 1999-05-19

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